This invention relates to directional beam forming antennas, and in particular to dielectric layer spatial filters for suppressing the sidelobes of beams transmitted by such antennas.
The performance of phased arrays and other directional beam forming antennas is often degraded by the presence of sidelobes and grating lobes in the transmitted beam. A particular problem is represented by the residual grating lobes that plague limited sector scanning and multiple beam arrays in airport precision-approach radar systems and synchronous satellite communications antennas. In the past, for each individual case, sidelobe problems have been overcome by redesigning the antenna. Such an approach is, of course, both inflexible and expensive. There currently exists, therefore, the need for greatly simplified, lightweight, inexpensive means for suppressing sidelobes and grating lobes in beams transmitted by directional beam-forming antennas. The present invention is directed toward satisfying that need.